This invention relates to solder joints, and more particularly, to solder containment structures that facilitate formation of satisfactory solder joints.
Electronic devices include electrical components such as resistors, capacitors, inductors, switches, light-emitting diodes, speakers, microphones, displays, integrated circuits, wires, connectors, and batteries. These electrical components are typically attached to a printed circuit board (PCB). The printed circuit board may, in turn, be mounted within the electronic device.
Some electrical components are attached to printed circuit boards using through-hole mounting techniques. This type of mounting technique is suitable for electrical components that have pins. The pins of an electrical component may be inserted into through-holes in a printed circuit board. For example, an electrical component may be attached onto a top surface of a printed circuit board so that its pins pass through corresponding through-holes. On the backside of the printed circuit board, the pins may protrude from the holes. Solder may be applied to the protruding end of the pin to electrically connect the pin to a solder pad that surrounds the protruding end of the pin. Solder joints form electrical connections between the electrical component and the solder pad and other traces on the printed circuit board.
Through-holes may consume undesirably large amounts of board area. For example, the presence of protruding backside pins may reduce backside mounting opportunities.
Another method of attaching electrical components to a printed circuit board involves the use of surface-mount technology (SMT) and SMT components. SMT mounting techniques involve the mounting of electronic components directly onto the surface of a printed circuit board. SMT techniques do not require the use of through-holes and may allow mirrored components to be placed on both surfaces of the printed circuit board (e.g., one component may be placed on the bottom surface directly below another component that is placed on the top surface).
In a typical SMT arrangement, a printed circuit board has solder pads that serve as landings for corresponding SMT contacts (leads) on an SMT component. Solder may be applied to the solder pads to form solder joints for the SMT component.
The use of these SMT mounting schemes may be suitable for mounting SMT parts to printed circuit boards. Other types of components may need to be connected differently. For example, batteries are often provided with wire leads. These leads may need to be soldered to solder pads on a printed circuit board. Unless care is taken, however, the solder joints that are used in connecting the wires to the printed circuit board may consume undesirably large amounts of area or may intrude into the space reserved for nearby components giving rise to potential component damage. A poorly formed solder joint might also contain insufficient solder, leading to an incomplete or unreliable connection.
It would therefore be desirable to be able to provide improved ways in which to form solder joints such as solder joints involved in soldering wires to solder pads on printed circuit boards.